I started to post a reply to January's discussion on ball turners but what the heck it's kinda spring-like and everything should start anew.

I just put some photos up on the Yahoo logan lathe site on my ball turner but since I spend very little time there (and I have a Logan), you probably don't either.

I still have to finish up making a real handle and I'm considering adding scale marks on the top. The unit replaces the compound and the carriage and cross slide are locked. All feeding of the tool (TNMG322)is done with the knob on the end. The inserts are set at 3 degrees and are set to the lathe centerline. When the radius cutter is puled all the way against the brass end, the tip of the insert spins at it's axis. The tool holder is reversible for grooving. My wife says I've got to start yard work now. -Mike

I've been building a very similar ball-turner for my 7x10 chicom pos. Yours is much nicer, both in design and finish than mine. There isn't enough room over the slide on mine to include a dovetail way.

Verne,
I have almost everything up to this point drawn up in autocad but it's not really in any kind of formal order blue-print wise, more like notes. I use autocad like other folks think out loud. I believe it would be really easy to change the base plate drawing to work on my SB9 as well. The critical dimension is the height from the top of the cross slide to the spindle centerline. My 820 measures 3.036" so I just made everything fit in-between. This turner will make a ball up to 2.88" in diameter (at least in autocad ).

I spent some time on Steve Bedaire's site and saw how he used setscrews to retain the tool holder. Does that mean that they have to be loosened and retightened each time the tool is adjusted for another pass? Another idea I wanted to try involved hobbing teeth around the circumference and making a worm setup to rotate it instead of using a handle. I gave that one up reluctantly only because I've never tried it (cutting teeth) before. Maybe next winter. -Mike

Yes, the same wrench is used for installation as the compound and can be accessed without disassembly. Unfortunately I don't think gun blue will work well since I made the body out of D-2. I may try though on an extra piece of material. I'm thinking powder coat since I have never done it and it would give me an excuse to get a set-up.

Jim, It's scary smooth and having a feed screw on the toolholder makes turning a ball very quick. I'm going to try some larger steel balls today as I need some inch and a halfers for an upcoming welding project. -Mike

I also make my own carbide insert toolholders for my lathe and have done some experimenting with angles between 0 and 5 degrees (sometimes compound angles). After figuring out what worked best, one day I stumbled on a catalog page in an insert mfg. catalog and noticed that all of their tool holders that used my shape of inserts had 5 degree negative rakes at the cutting edges.

In my experimenting I found that without a negative rake (cutting tip down) the tip chips off quickly and the front of the insert just rubs against the material. With a negative rake, even when the tip chips badly there is still relief (3-5 degrees) under the tip and it will still continue to cut. Unless you buy inserts with a rake built in, they're usually straight on the end. The insert mfg's customers are mostly using very rigid CNC machines with lots of torque and can use -5 degrees without issue. I split the difference for my old manual lathe and -3 degrees works best for me. -Mike

Very impressive! That's got to be the nicest radius-turning attachment I've seen this side of a CNC lathe. Really makes me look forward to the day when I have a fully-functioning shop again. Thanks very much for the pictures and words!

Thanks everybody for the kind words. I'm not sure exactly how to go about it, but since so many are interested in plans, I will make them available for free?. If I find time this weekend to clean up the drawing and add the little details like thread sizes that I used and minor things like that, I can try to scan a hardcopy into a PDF file so everyone can read it.
I didn't intend to go into the ball turner business, just want to have fun in my home shop. I hope you do too. -Mike

Mike, I can only speak for myself. It sounds like you have quite a bit of time invested in this and your time is worth money. I will be "more" than glad to pay you for a copy of the plans. You have a tallent, don't sell yourself short. If nothing else, just another way to buy more "toys". Honor and Respect

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